Alloy for permanent magnets



Patented Jan. 18, 1938 UNITED STATES PATENT OFFICE '*.Z1.Zli.....'f

No Drawing. Application November 19, 1935, Serial No. 50,617. In Japan May 1, 1033 60laims. .(CL 75-123) This application forms acontinuation in part of my copending application Ser. No. 735,898 filed July 18, 1934 and also of the parent application Ser. No. 697,874, filed November 13, 1933,

both pending. 1 I

This invention relates to improvements in al- -loys for permanent magnetsand more particularly to an alloy consisting mainly of nickel, titanium, cobalt and'iron', and has for its. object to provide a permanent magnet which has a very high coercive force and long durability.

' Heretoi'ore commonly used magnet steels such as tungsten steel, chrome steel and the like have comparatively small coercive force of only 60 to '70 gausses and if such alloy steels are'used as a permanent magnet they lack durability and are especially unsuitable fora magnet of smaller dimension-ratio, that is, having a small ratio of the length and diameter. Moreover, such alloy steels are greatly afiected by temperature variations and mechanical shocks and show unstable magnetic properties.

This invention is to obviate the above mentioned defects and to provide an alloy which smaller dimension-ratio, and possesses stable magnetic properties for temperature changes and mechanical shocks and has particularly high der iron and a small amount of impurities. The

preferred composition of the alloy may be of 5 to 19.9% nickel, 5 to 10% titanium, 3 to cobalt and the remainder iron. The molten product may be cast in a suitable mold or sucked up into a tube of refractory material to give a desired shape. The cast products are preferably annealed at a suitable temperature such as 500 to 800 C. to give it stability.-

As above described, though the-alloy of this invention may be obtained by melting together iron, nickel, cobalt and titanium at a proper proportion, yet it is more convenient in practice to use iron or mild steel, nickel, cobalt and ferro-titanium.

As for example, the following alloy of this in- Such magnetic properties are obtained by casting the alloy and afterwards annealing it at about 670 C. for two hours. It will be recogis well adapted for a permanent magnet 01 'a' nized that the above alloy shows particularly high coercive force.

' The alloys of the present invention may also contain manganese, molybdenum. arsenic, va-

- nadium, copper and aluminium in the proportion of less than 6% each for a further increase of the residual magnetic induction and the coercive force, 1 I

Accordingly the alloy of this invention is well adapted for the material of permanent magnets in general and more especially of smaller dimen- .-sion-ratio and it has very stable structure at a temperature below about 700 C. and its mag- .netic properties are not substantially aflected by permanent magnets. 1

What I claim as new and desire. to secure by Letters Patent 01 the United States, is:

1. A permanent magnet formed .01 an alloy consisting of 3 to 19.9% nlckel,'3 to 10% tita-.

nium, 7.5 to 60% cobalt. molybdenum in an amount-lessv than 6%, and the remainder iron formed by casting the alloy to a desired shape and then annealing it at a-temperature of from 500 C. to 800 C, to increase the coercive force thereof to the neighborhood '0! more. v 2. A permanent magnet of very high coercive force and long durability formed or an alloy containing 3 to 19.9% nickel, 3 to 10% titanium, .5-6.0% cobalt, molybdenum in an amount less than 6%, and the remainder iron and a small amount of impurities, characterized by a coercive force in the neighborhood of 250 gausses or more.

3. A permanent magnet of very high coercive 250 gausses or force and'long durability formed of an alloy containing 5 to 19.9% of nickel, 5 to 10% of titanium, 3 to 35% ofcobalt, molybdenum in anamount less than 6%, and the remainder iron I and a small amount of impurities. characterized by a coercive force in the neighborhood of 250 gausses or more.-

4. A permanentmagnet having a small ratio of length to diameter formed or an alloy containing as essential ingredients 3 to 19.9% of nickel, 3 to 10% of titanium, 0.5 to 60% of cobait, molybdenum in an amount less than 6%, and the remainder iron and a small amount 01' impurities, characterized by a coercive force in the neighborhood of 250 gausses or more, long durability and magnetic stability with respect to temperature changes and mechanical shocks.

5. A permanent-magnet having a small ratio the remainder iron and a. small amount 01 im-- purities characterized by a coercive force in the of nickel, about 7.4% of titanium and about 9% neighborhood of 250 gausses or more, long duracobalt, molybdenum in an amount less than 6%. bility and magnetic stability with respect to temand the remainder ironand a small amount of perature changes and mechanical shocks. impurities characterized by a coercive force of 6. A permanent magnet formed of an alloy about 810 gausses. 5.

containing as essential ingredients about 16.5%- t KbTARO HONDA. 

